Intimate Protective Layer via Lithiation Sintering for All-Solid-State Lithium Metal Batteries

In the pursuit of safer and more energy-dense battery systems, all-solid-state lithium metal batteries (ASSLMBs) have emerged as an attractive alternative with significant potential to conventional lithium-ion batteries (LIBs). However, numerous protective layers proposed to passivate the Li metal anodes suffer from low ionic conductivity and high local current density due to interfacial contact loss. Here, we address these challenges by developing an intimate protective layer with high ionic conductivity, synthesized through a pressure-induced lithiation sintering process. During lithiation, nanosized Si (nSi) particles expand and sinter together into a compact layer with intimate contact. This process yields a pore-free nSi-Li layer that integrates seamlessly with the electrolyte layer. The unique morphology of this layer results in reduced overpotential and local current density, enabling stable and reversible 2-dimensional lithium plating and stripping. These findings highlight the importance of morphological effects in protective layers, thus marking a significant step forward in solid-state battery technology.